High power klystron

ABSTRACT

A high power klystron including means for forming an electron beam, preferably a hollow electron beam, with a perveance which is greater than 3 and means for defining interaction paths including delay line type structures in resonator chambers as sections with extended interaction.

United States Patent Heynisch et al.

[ 1 Aug. 29, 1972 [54] HIGH POWER KLYSTRON [72] Inventors: HinrichHeynisch, Graefelfing; Hannioerg Bittorf, Munich, both of Germany [73]Assignee: Siemens Aktiengesellschaft, Berlin and Munich, Germany [22]Filed: March 3, 1971 [21] Appl. No.: 120,394

[30] Foreign Application Priority Data March 5, 1970 Germany ..P 20 10480.7

[52] U.S. Cl ..3l5/5.31, 315/539, 333/83 R [51] Int. Cl ..H01j 25/14[58] Field of Search ..3l5/5.31, 5.39, 5.29

[56] References Cited UNITED STATES PATENTS 3,270,240 8/1966 Lavoo..315/539 X 7 2,659,024 11/1953 Bernier et a1. ..315/531 X 3,130,3404/1964 Koziak ..315/5.31 X 2,316,264 4/1943 Litton ..315/5'.3l 2,945,1557/1960 Chodorow ..315/539 3,375,397 3/1968 Leidigh et a1 ..315/5.5l X3,453,483 7/1969 Leidigh ..315/5.39 2,466,064 4/ 1949 Wathen et a1...315/5.31

Primary Examiner-Herman Karl Saalbach Assistant Examiner-SaxfieldChatmon, Jr. Attorney-Hill, Sherman, Meroni, Gross & Simpson ABSTRACT Ahigh power klystron including means for forming an electron beam,preferably a hollow electron beam, with a perveance which is greaterthan 3 and means for defining interaction paths including delay linetype structures in resonator chambers as sections with extendedinteraction.

ICIaiImIDraWingFigure 1 HIGH POWER KLYSTRON BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to high powerklystron particularly for television transmission, with an electron beamproducing system, in which a number of resonator chambers are permeatedby an electron beam which is extended therethrough in a reduced beambundle, and an electron beam collector device.

2. Description of the Prior Art High power klystrons are preferablyutilized in the ultra high frequency (UHF) range for the transmission oftelevision programs, whereby high transmission qualities are of primaryimportance in the UHF range. In order to comply with the high demandsplaced on the transmission and in particular to the requirement forlinearity in amplification, klystrons for television applications mustbe operated with a beam perveance of the electron beam which is smallerthan 2 (reference here being taken to Rundfunkteschnische Mitteilungen,volume 12, 1968, issue 6, pages 262-268, as well as NTZ, 1966, issue 6,beginning at page 365). The reason for this is that the high, merelypositive, electron stress on the resonators due to the electron beam. Itis furthermore stated that, in order to obtain the television qualitiesrequired, the qualities of the resonators should essentially bedetermined by the externally applied stress.

SUMMARY OF THE INVENTION In contrast to these prior art klystrons fortelevision applications, it is proposed according to the presentinvention that a high power klystron of the above-mentioned kind have aperveance which is greater than 3 for the electron beam, which beam ispreferably formed as a hollow beam, and that the interaction paths aredesigned as sections with extensive interaction by providing delay linelike structures, which structures are known per se, in the resonatorchambers of the klystron.

Klystrons with extended interaction, generally called ExtendedInteraction Klystrons are known in the art, they have heretofore beendriven with electron beams having a perveance that is less than 2. Here,compare IRE TRANSACTIONS ON ELECTRON DEVICES, January 1961, pages 44-55,in particular at page 49, left-hand column near the bottom.

The present invention therefore proceeds from the recognition that theelectron stress depends strongly on the beam speed in a resonator cavitywith distributed or strongly extended interaction. With a suitableselection of the beam speed, the electronic stress can be made almostzero. This is alsovalid for perveance values which are greater than 2(i.e. 2- A/V It has been shown that the perveance of the electron beamis only limited by the fact that the average center geometric distanceof two successive resonators must be a fourth of the plasma wave length,and thereby the resonator chambers are still sufficiently decoupled withrespect to high frequency.

BRIEF DESCRIPTION OF THE DRAWING Other objects, features and advantagesof the invention will be best understood from the following detaileddescription taken in conjunction with the accompanying drawing whichcarries a single FIGURE showing an elevational cross-sectional view of ahigh power klystron constructed in accordance with the principles of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, ahighly perrneant hollow electron beam 18 is produced by an electron beamproducing system 1 which comprises a wing-shaped cathode 2, which has anend thereof surrounded by Wehnelt electrode 3. A pulling anode 4 ispreferably defined as a modulation anode and is disposed adjacent to theelectrode 3 and generally aligned therewith axially of the klystron. Theelectron beam 18 traverses the klystron generally about the longitudinalaxis thereof to reach an electron beam collector 8 which is providedwith cooling plates 7, after first having permeated a series ofresonator chambers 5 and 6. Suitablyv arranged and dimensionedelectromagnets 9 are provided to effect guidance of the electron beamthrough the tube without permitting radial dispersion of the beam, theentire magnet arrangement being preferably arranged between a pair ofpole plates 10.

The sample embodiment set forth in the figure illustrates a klystronhaving a plurality of chambers, say a five-chamber klystron, and for thesake of simplicity, the second and third chambers have. not beenillustrated, which chambers are however constructed'to correspond to theresonator chambers 5. The fifth resonator chamber 6 differs somewhatfrom the construction of the preceding resonator chambers 5 in order toprovide an optimum adaptation of the reduced electron beam speed.Spiral-shaped delay structures 11 and 12 are provided in the resonatorchambers in order to form a broad-band extended interaction zonecorresponding to the aforementioned and so-called extended interaction,in place of the usually narrowband interaction between the beam andinteraction gaps.

In order to prevent interfering backward-facing waves on the delaysections 11 and 12, measures have been provided which are in themselvesknown in the art and which are not illustrated here for the sake ofsimplicity and clarity. The delay structures 11 and 12 are connectedwith internal conductors 13, 14 and 15 of coaxial decoupling memberswhich are respectively sealed with respect to the vacuum within theresonator chambers by means of ceramic windows, the windows 16 and 17being illustrated in the drawing.

Although we have described our invention by reference to a specificillustrative embodiment, many changes and modifications may be effectedby those skilled in the art without departing from the spirit and scopeof our invention, and it is to be understood that we intend to includewithin the patent warranted hereon all such changes and modifications asmay reasonably and properly be included within the scope of ourcontribution to the art.

WHAT WE CLAIM IS:

1. In a high power extended. interaction klystron of the type whichincludes an electron beam producing system, a number of resonatorchambers which are permeated with an electron beam which is extended ina reduced bundle, and an electron beam collector for receiving theelectron beam, the improvement therein comprising means for producingthe electron beam as a hollow beam with a perveance which is greaterthan 3, and means defining interaction paths including delay 5 linestructures in the resonator chambers which are operable as sections withextended interaction.

1. In a high power extended interaction klystron of the type whichincludes an electron beam producing system, a number of resonatorchambers which are permeated with an electron beam which is extended ina reduced bundle, and an electron beam collector for receiving theelectron beam, the improvement therein comprising means for producingthe electron beam as a hollow beam with a perveance which is greaterthan 3, and means defining interaction paths including delay linestructures in the resonator chambers which are operable as sections withextended interaction.